We report on the development of a fast neutron detector using a liquid scintillator doped with enriched 6Li. The lithium was introduced in the form of an aqueous LiCl micro-emulsion with a di-isopropylnaphthalene based liquid scintillator. A 6Li concentration of 0.15% by weight was obtained. A 125mL glass cell was filled with the scintillator and irradiated with fi ssion-source neutrons. Fast neutrons produce recoil protons in the scintillator, and those neutrons that thermalize within the detector volume may be captured on the 6Li. The energy of the neutron may be determined by the light output from recoiling protons, and the capture of the delayed thermal neutron reduces background events. In this paper, we discuss the development of this 6Li-loaded liquid scintillator, demonstrate the operation of it in a detector, and compare its efficiency and capture lifetime with Monte Carlo simulations. Data from a boron-loaded plastic scintillator were acquired for comparison. We also present a pulse-shape discrimination method for di erentiating between electronic and nuclear recoil events based on the Matusita distance between a normalized observed waveform and nuclear and electronic recoil template waveforms. The details of the measurements are discussed along with speci cs of the data analysis and its comparison with the Monte Carlo simulation.
Citation: Nuclear Instruments & Methods A
Pub Type: Journals
capture-gated spectroscopy, fast neutron, lithium-6, neutron detection, neutron spectroscopy